/Engine/Source/Editor/Kismet/Public/BlueprintAssetHandler.h
Any assets whose class is a child of the specified class will use this handler (unless there is a more specific handler registered)
void RegisterHandler ( [FTopLevelAssetPath](API\Runtime\CoreUObject\UObject\FTopLevelAssetPath) ClassPathName, [TUniquePtr](API\Runtime\Core\Templates\TUniquePtr)< [IBlueprintAssetHandler](API\Editor\Kismet\IBlueprintAssetHandler) > && InHandler )